The Lies We Tell

Zed Shaw teaches a course in writing Python called “Python the Hard Way“. Because the hard way is easier, he says.

In the end, he’s right. If you really want to learn organic chemistry, the hard way is easier. In graduate school I had to un-learn a lot of the half-truths I was taught in the introductory courses I took as a chemistry major and it still angers me somewhat that nobody thought to give me the straight dope. A lot of the reactions (and reagents, especially) that are covered in a typical sophomore class bear faint resemblance to reactions you’d ever bother using if you became a professional organic chemist. Not only that, some of the concepts are half-truths too.

But half-truths are easier and faster to teach. The “easy way” to get across organic chemistry is to oversimplify things. I do it all the time. Every instructor does it to some extent. Something is true 98% of the time, so we lie and say it’s “always” true.

Look out for the words “always” and “never” – they’re the cloaks we use for our lies of omission.

Why tell these lies of omission? Because they save time. It can take a lot of time and effort to bother explaining all the exceptions to the rules, and for the purpose of the class, they’re not always crucially important. Time is limited. The attention of the class can be limited. And let’s be honest – the talent of the class can be limited too. With some students, you’re delighted if you can just get the basic concepts across.

Furthermore, many students don’t really want to learn organic chemistry per se. What they want is a line on their transcript that states that they have taken a course in organic chemistry, and done acceptably well relative to the rest of the class. That’s just the way it is sometimes. I’m fine with that.

But it doesn’t mean that somewhere it can’t be said that – “we’re only giving you a part of the story here”, or “this explanation will have to do for now”. So you can think of this post as kind of a penance for all the lies I’ve helped to perpetuate in my short time as a freelance instructor.

So here are some of the most common lies I’ve told, and an attempt to impart more of the “whole truth”.

I can’t find it right now, but I am looking for a quote I read somewhere that said something like:

“Progress in teaching a course can be measured by the necessity of telling smaller and smaller lies. “

It works OK, you just need to protect the amine as an amide. Then it will work. I would recommend your friend read the relevant section in March’s Advanced Organic Chemistry, this point and many others will become more clear.

Did you ever see the 2007 rebuttal in JACS to the classic Nature paper on the ethane rotational barrier? After more calculations and lots of stuff I don’t understand the authors concluded the origin to be about 25% hyperconjugation and 75% sterics. I don’t know enough computational chemistry to comment on the validity of this conclusion. Some references and free commentary at http://comporgchem.com/blog/?p=37. I have a feeling a saw an even more recent paper on this, but I can’t find it at the moment.

As a current PhD student I’m still trying to unlearn the lies of my undergraduate courses. A couple of weeks ago I saw DBU used in a Baylis Hillman reaction. There goes another one.

The ‘lie’ was that DBU is a non nucleophilic base, and doesn’t do things like add to unsaturated esters. I agree that ethane’s a good way to introduce the concept of hyperconjugation (well, that or cation stability as you say).

Ha! yeah, there’s really no such thing as a “non-nucleophilic base”, or even a “non-coordinating solvent”. There have been metal complexes isolated with CH2Cl2 as a ligand for example (among many others).